It is known that for the cold gas spraying method (ColdSpray™, “Kinetic Gas Spray”, see DE 69016433 T2, EP 0 484 553 A1, U.S. Pat. No. 5,302,414 A1, US 2004/037954, EP 0 924 315 B1, EP 1 132 497 A1, U.S. Pat. No. 6,502,767 B2), for coating purposes, the powdered materials employed must have particle sizes of >5 μm, ideally from 20 to 40 μm. For kinetic energy reasons, the direct spraying of nanoparticulate materials in order to achieve directly nanostructured or thin-layer coatings (<1 μm) is not possible. Particles with sizes <5 μm will not be incorporated into the layers; rather, even before impact on the substrate they will preferentially be deflected laterally by the stagnation pressure being formed in front of the substrate. It is furthermore known that continuously accelerated carrier gas flows in the ultrasonic range, restricted to 2000 m/s, are used in the cold gas spraying method.
U.S. Pat. No. 6,124,563 A1 and U.S. Pat. No. 6,630,207 B1 describe pulsed thermal spraying methods (pulsed HVOF, pulsed Railgun, pulsed electrothermal & plasma spraying methods) with which particle velocities >>2000 m/s can be achieved. Improved layer properties and layer systems can thereby be produced, which hitherto were not achievable owing to low particle velocities.
DE 103 19 481 A1 and WO 03/041868 A2 describe special nozzle designs for cold gas spraying methods. EP 1 132 497 A1 describes unrelatedly the effect of pulsating particle dosing.